/*
 *  Simple DTLS server demonstration program
 *
 *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
 *  SPDX-License-Identifier: Apache-2.0
 *
 *  Licensed under the Apache License, Version 2.0 (the "License"); you may
 *  not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 *  This file is part of mbed TLS (https://tls.mbed.org)
 */

#if !defined(MBEDTLS_CONFIG_FILE)
#include "mbedtls/config.h"
#else
#include MBEDTLS_CONFIG_FILE
#endif

#if defined(MBEDTLS_PLATFORM_C)
#include "mbedtls/platform.h"
#else
#include <stdio.h>
#define mbedtls_printf     printf
#define mbedtls_fprintf    fprintf
#endif

#if !defined(MBEDTLS_SSL_SRV_C) || !defined(MBEDTLS_SSL_PROTO_DTLS) ||    \
	!defined(MBEDTLS_SSL_COOKIE_C) || !defined(MBEDTLS_NET_C) ||          \
	!defined(MBEDTLS_ENTROPY_C) || !defined(MBEDTLS_CTR_DRBG_C) ||        \
	!defined(MBEDTLS_X509_CRT_PARSE_C) || !defined(MBEDTLS_RSA_C) ||      \
	!defined(MBEDTLS_CERTS_C) || !defined(MBEDTLS_PEM_PARSE_C) ||         \
	!defined(MBEDTLS_TIMING_C)

int main( void )
{
	printf( "MBEDTLS_SSL_SRV_C and/or MBEDTLS_SSL_PROTO_DTLS and/or "
			"MBEDTLS_SSL_COOKIE_C and/or MBEDTLS_NET_C and/or "
			"MBEDTLS_ENTROPY_C and/or MBEDTLS_CTR_DRBG_C and/or "
			"MBEDTLS_X509_CRT_PARSE_C and/or MBEDTLS_RSA_C and/or "
			"MBEDTLS_CERTS_C and/or MBEDTLS_PEM_PARSE_C and/or "
			"MBEDTLS_TIMING_C not defined.\n" );
	return( 0 );
}
#else

#if defined(_WIN32)
#include <windows.h>
#endif

#include <string.h>
#include <stdlib.h>
#include <stdio.h>

#include "mbedtls/entropy.h"
#include "mbedtls/ctr_drbg.h"
#include "mbedtls/certs.h"
#include "mbedtls/x509.h"
#include "mbedtls/ssl.h"
#include "mbedtls/ssl_cookie.h"
#include "mbedtls/net.h"
#include "mbedtls/error.h"
#include "mbedtls/debug.h"
#include "mbedtls/timing.h"

#if defined(MBEDTLS_SSL_CACHE_C)
#include "mbedtls/ssl_cache.h"
#endif

#define READ_TIMEOUT_MS 10000   /* 5 seconds */
#define DEBUG_LEVEL 0

mbedtls_net_context listen_fd, client_fd;
mbedtls_ssl_cookie_ctx cookie_ctx;
mbedtls_entropy_context entropy;
mbedtls_ctr_drbg_context ctr_drbg;
mbedtls_ssl_context ssl;
mbedtls_ssl_config conf;
mbedtls_x509_crt srvcert;
mbedtls_pk_context pkey;
mbedtls_timing_delay_context timer;
#if defined(MBEDTLS_SSL_CACHE_C)
mbedtls_ssl_cache_context cache;
#endif
unsigned char buf[1024];

static void my_debug( void *ctx, int level,
					  const char *file, int line,
					  const char *str )
{
	((void) level);

	mbedtls_fprintf( (FILE *) ctx, "%s:%04d: %s", file, line, str );
	fflush(  (FILE *) ctx  );
}

int main( void )
{
	int ret, len;
	const char *pers = "dtls_server";
	unsigned char client_ip[16] = { 0 };
	size_t cliip_len;

	mbedtls_net_init( &listen_fd );
	mbedtls_net_init( &client_fd );
	mbedtls_ssl_init( &ssl );
	mbedtls_ssl_config_init( &conf );
	mbedtls_ssl_cookie_init( &cookie_ctx );
#if defined(MBEDTLS_SSL_CACHE_C)
	mbedtls_ssl_cache_init( &cache );
#endif
	mbedtls_x509_crt_init( &srvcert );
	mbedtls_pk_init( &pkey );
	mbedtls_entropy_init( &entropy );
	mbedtls_ctr_drbg_init( &ctr_drbg );

#if defined(MBEDTLS_DEBUG_C)
	mbedtls_debug_set_threshold( DEBUG_LEVEL );
#endif

	/*
	 * 1. Load the certificates and private RSA key
	 */
	printf( "\n  . Loading the server cert. and key..." );
	fflush( stdout );

	/*
	 * This demonstration program uses embedded test certificates.
	 * Instead, you may want to use mbedtls_x509_crt_parse_file() to read the
	 * server and CA certificates, as well as mbedtls_pk_parse_keyfile().
	 */
	ret = mbedtls_x509_crt_parse( &srvcert, (const unsigned char *) mbedtls_test_srv_crt,
						  mbedtls_test_srv_crt_len );
	if( ret != 0 )
	{
		printf( " failed\n  !  mbedtls_x509_crt_parse returned %d\n\n", ret );
		goto exit;
	}

	ret = mbedtls_x509_crt_parse( &srvcert, (const unsigned char *) mbedtls_test_cas_pem,
						  mbedtls_test_cas_pem_len );
	if( ret != 0 )
	{
		printf( " failed\n  !  mbedtls_x509_crt_parse returned %d\n\n", ret );
		goto exit;
	}

	ret =  mbedtls_pk_parse_key( &pkey, (const unsigned char *) mbedtls_test_srv_key,
						 mbedtls_test_srv_key_len, NULL, 0 );
	if( ret != 0 )
	{
		printf( " failed\n  !  mbedtls_pk_parse_key returned %d\n\n", ret );
		goto exit;
	}

	printf( " ok\n" );

	/*
	 * 2. Setup the "listening" UDP socket
	 */
	printf( "  . Bind on udp/*/4433 ..." );
	fflush( stdout );

	if( ( ret = mbedtls_net_bind( &listen_fd, NULL, "4433", MBEDTLS_NET_PROTO_UDP ) ) != 0 )
	{
		printf( " failed\n  ! mbedtls_net_bind returned %d\n\n", ret );
		goto exit;
	}

	printf( " ok\n" );

	/*
	 * 3. Seed the RNG
	 */
	printf( "  . Seeding the random number generator..." );
	fflush( stdout );

	if( ( ret = mbedtls_ctr_drbg_seed( &ctr_drbg, mbedtls_entropy_func, &entropy,
							   (const unsigned char *) pers,
							   strlen( pers ) ) ) != 0 )
	{
		printf( " failed\n  ! mbedtls_ctr_drbg_seed returned %d\n", ret );
		goto exit;
	}

	printf( " ok\n" );

	/*
	 * 4. Setup stuff
	 */
	printf( "  . Setting up the DTLS data..." );
	fflush( stdout );

	if( ( ret = mbedtls_ssl_config_defaults( &conf,
					MBEDTLS_SSL_IS_SERVER,
					MBEDTLS_SSL_TRANSPORT_DATAGRAM,
					MBEDTLS_SSL_PRESET_DEFAULT ) ) != 0 )
	{
		mbedtls_printf( " failed\n  ! mbedtls_ssl_config_defaults returned %d\n\n", ret );
		goto exit;
	}

	mbedtls_ssl_conf_rng( &conf, mbedtls_ctr_drbg_random, &ctr_drbg );
	mbedtls_ssl_conf_dbg( &conf, my_debug, stdout );

#if defined(MBEDTLS_SSL_CACHE_C)
	mbedtls_ssl_conf_session_cache( &conf, &cache,
								   mbedtls_ssl_cache_get,
								   mbedtls_ssl_cache_set );
#endif

	mbedtls_ssl_conf_ca_chain( &conf, srvcert.next, NULL );
   if( ( ret = mbedtls_ssl_conf_own_cert( &conf, &srvcert, &pkey ) ) != 0 )
	{
		printf( " failed\n  ! mbedtls_ssl_conf_own_cert returned %d\n\n", ret );
		goto exit;
	}

	if( ( ret = mbedtls_ssl_cookie_setup( &cookie_ctx,
								  mbedtls_ctr_drbg_random, &ctr_drbg ) ) != 0 )
	{
		printf( " failed\n  ! mbedtls_ssl_cookie_setup returned %d\n\n", ret );
		goto exit;
	}

	mbedtls_ssl_conf_dtls_cookies( &conf, mbedtls_ssl_cookie_write, mbedtls_ssl_cookie_check,
							   &cookie_ctx );

	if( ( ret = mbedtls_ssl_setup( &ssl, &conf ) ) != 0 )
	{
		printf( " failed\n  ! mbedtls_ssl_setup returned %d\n\n", ret );
		goto exit;
	}

	mbedtls_ssl_set_timer_cb( &ssl, &timer, mbedtls_timing_set_delay,
											mbedtls_timing_get_delay );

	printf( " ok\n" );

reset:
#ifdef MBEDTLS_ERROR_C
	if( ret != 0 )
	{
		char error_buf[100];
		mbedtls_strerror( ret, error_buf, 100 );
		printf("Last error was: %d - %s\n\n", ret, error_buf );
	}
#endif

	mbedtls_net_free( &client_fd );

	mbedtls_ssl_session_reset( &ssl );

	/*
	 * 3. Wait until a client connects
	 */
	printf( "  . Waiting for a remote connection ..." );
	fflush( stdout );

	if( ( ret = mbedtls_net_accept( &listen_fd, &client_fd,
					client_ip, sizeof( client_ip ), &cliip_len ) ) != 0 )
	{
		printf( " failed\n  ! mbedtls_net_accept returned %d\n\n", ret );
		goto exit;
	}

	/* For HelloVerifyRequest cookies */
	if( ( ret = mbedtls_ssl_set_client_transport_id( &ssl,
					client_ip, cliip_len ) ) != 0 )
	{
		printf( " failed\n  ! "
				"mbedtls_ssl_set_client_transport_id() returned -0x%x\n\n", -ret );
		goto exit;
	}

	mbedtls_ssl_set_bio( &ssl, &client_fd,
						 mbedtls_net_send, mbedtls_net_recv, mbedtls_net_recv_timeout );

	printf( " ok\n" );

	/*
	 * 5. Handshake
	 */
	printf( "  . Performing the DTLS handshake..." );
	fflush( stdout );

	do ret = mbedtls_ssl_handshake( &ssl );
	while( ret == MBEDTLS_ERR_SSL_WANT_READ ||
		   ret == MBEDTLS_ERR_SSL_WANT_WRITE );

	if( ret == MBEDTLS_ERR_SSL_HELLO_VERIFY_REQUIRED )
	{
		printf( " hello verification requested\n" );
		ret = 0;
		goto reset;
	}
	else if( ret != 0 )
	{
		printf( " failed\n  ! mbedtls_ssl_handshake returned -0x%x\n\n", -ret );
		goto reset;
	}

	printf( " ok\n" );

	/*
	 * 6. Read the echo Request
	 */
	printf( "  < Read from client:" );
	fflush( stdout );

	len = sizeof( buf ) - 1;
	memset( buf, 0, sizeof( buf ) );

	do ret = mbedtls_ssl_read( &ssl, buf, len );
	while( ret == MBEDTLS_ERR_SSL_WANT_READ ||
		   ret == MBEDTLS_ERR_SSL_WANT_WRITE );

	if( ret <= 0 )
	{
		switch( ret )
		{
			case MBEDTLS_ERR_SSL_TIMEOUT:
				printf( " timeout\n\n" );
				goto reset;

			case MBEDTLS_ERR_SSL_PEER_CLOSE_NOTIFY:
				printf( " connection was closed gracefully\n" );
				ret = 0;
				goto close_notify;

			default:
				printf( " mbedtls_ssl_read returned -0x%x\n\n", -ret );
				goto reset;
		}
	}

	len = ret;
	printf( " %d bytes read\n\n%s\n\n", len, buf );

	/*
	 * 7. Write the 200 Response
	 */
	printf( "  > Write to client:" );
	fflush( stdout );

	do ret = mbedtls_ssl_write( &ssl, buf, len );
	while( ret == MBEDTLS_ERR_SSL_WANT_READ ||
		   ret == MBEDTLS_ERR_SSL_WANT_WRITE );

	if( ret < 0 )
	{
		printf( " failed\n  ! mbedtls_ssl_write returned %d\n\n", ret );
		goto exit;
	}

	len = ret;
	printf( " %d bytes written\n\n%s\n\n", len, buf );

	/*
	 * 8. Done, cleanly close the connection
	 */
close_notify:
	printf( "  . Closing the connection..." );

	/* No error checking, the connection might be closed already */
	do ret = mbedtls_ssl_close_notify( &ssl );
	while( ret == MBEDTLS_ERR_SSL_WANT_WRITE );
	ret = 0;

	printf( " done\n" );

	goto reset;

	/*
	 * Final clean-ups and exit
	 */
exit:

#ifdef MBEDTLS_ERROR_C
	if( ret != 0 )
	{
		char error_buf[100];
		mbedtls_strerror( ret, error_buf, 100 );
		printf( "Last error was: %d - %s\n\n", ret, error_buf );
	}
#endif

	mbedtls_net_free( &client_fd );
	mbedtls_net_free( &listen_fd );

	mbedtls_x509_crt_free( &srvcert );
	mbedtls_pk_free( &pkey );
	mbedtls_ssl_free( &ssl );
	mbedtls_ssl_config_free( &conf );
	mbedtls_ssl_cookie_free( &cookie_ctx );
#if defined(MBEDTLS_SSL_CACHE_C)
	mbedtls_ssl_cache_free( &cache );
#endif
	mbedtls_ctr_drbg_free( &ctr_drbg );
	mbedtls_entropy_free( &entropy );

#if defined(_WIN32)
	printf( "  Press Enter to exit this program.\n" );
	fflush( stdout ); getchar();
#endif

	/* Shell can not handle large exit numbers -> 1 for errors */
	if( ret < 0 )
		ret = 1;

	return( ret );
}
#endif /* MBEDTLS_SSL_SRV_C && MBEDTLS_SSL_PROTO_DTLS &&
		  MBEDTLS_SSL_COOKIE_C && MBEDTLS_NET_C && MBEDTLS_ENTROPY_C &&
		  MBEDTLS_CTR_DRBG_C && MBEDTLS_X509_CRT_PARSE_C && MBEDTLS_RSA_C
		  && MBEDTLS_CERTS_C && MBEDTLS_PEM_PARSE_C && MBEDTLS_TIMING_C */
